Treatment of Septage Using an Upflow Anaerobic Sludge Blanket Reactor

Abstract

This study examined the feasibility of applying an upflow anaerobic sludge blanket (UASB) reactor to treat septage. The UASB reactor was operated at 35 ± 1 °C, and the substrate septage had a total solids (TS) concentration of 13 200 mg/L. Reactor operation was initiated at a hydraulic residence time (HRT) of 10 days; thereafter, the HRT was shortened stepwise to 1.5 days. The TS, volatile solids (VS), and organic loading rates were 1.4 to 9.4 kg TS/m3·d, 5.6 to 8.5 kg VS/m3·d, and 1.1 to 6.7 kg chemical oxygen demand (COD)/m3·d, respectively. At the organic loading rate of 6.7 kg COD/m3·d (the HRT of 1.5 days), the total COD, soluble COD, and TS and VS removal efficiencies were 68, 74, and 66 and 73%, respectively. The average granule diameter and volatile suspended solids concentration were approximately 0.89 mm and 32 000 mg/L, respectively. Based on results obtained from 7 months of constant methane production and removal efficiencies, which are comparable to values previously reported in the literature for wastewater, it was concluded that a UASB reactor can successfully treat septage.